Return-path: Received: from mail-ie0-f174.google.com ([209.85.223.174]:47883 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174Ab2IHMht (ORCPT ); Sat, 8 Sep 2012 08:37:49 -0400 Received: by ieje11 with SMTP id e11so560373iej.19 for ; Sat, 08 Sep 2012 05:37:49 -0700 (PDT) Message-ID: <504B3C19.5040405@lwfinger.net> (sfid-20120908_143753_708949_60128D64) Date: Sat, 08 Sep 2012 07:37:45 -0500 From: Larry Finger MIME-Version: 1.0 To: Wei Yongjun CC: lauro.venancio@openbossa.org, aloisio.almeida@openbossa.org, sameo@linux.intel.com, yongjun_wei@trendmicro.com.cn, linux-wireless@vger.kernel.org Subject: Re: [PATCH v2] NFC: pn544_hci: move the dereference below the NULL test References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 09/07/2012 10:34 PM, Wei Yongjun wrote: > On 09/08/2012 10:03 AM, Larry Finger wrote: >> On 09/07/2012 08:53 PM, Wei Yongjun wrote: >>> From: Wei Yongjun >>> >>> The dereference should be moved below the NULL test. >>> >>> spatch with a semantic match is used to found this. >>> (http://coccinelle.lip6.fr/) >>> >>> Signed-off-by: Wei Yongjun >>> --- >>> >> >> As long as you are reworking this section, doesn't BUG_ON seem a little harsh? I do not think the kernel should ever be crashed because a non-essential driver is messed up. As the patch would be a totally different change, it should be a new submission, but I think each of these conditions should trigger a WARN_ON_ONCE, and return IRQ_NONE when they occur. >> > You means the should be like this? > > diff --git a/drivers/nfc/pn544_hci.c b/drivers/nfc/pn544_hci.c > index aa71807..e42b100 100644 > --- a/drivers/nfc/pn544_hci.c > +++ b/drivers/nfc/pn544_hci.c > @@ -341,13 +341,16 @@ flush: > static irqreturn_t pn544_hci_irq_thread_fn(int irq, void *dev_id) > { > struct pn544_hci_info *info = dev_id; > - struct i2c_client *client = info->i2c_dev; > + struct i2c_client *client; > struct sk_buff *skb = NULL; > int r; > > - BUG_ON(!info); > - BUG_ON(irq != info->i2c_dev->irq); > + if (!info || irq != info->i2c_dev->irq) { > + WARN_ON_ONCE(1); > + return IRQ_NONE; > + } > > + client = info->i2c_dev; > dev_dbg(&client->dev, "IRQ\n"); > > if (info->hard_fault != 0) Yes, that looks better to me. Larry